Implantable neurostimulators are used to deliver neurostimulation therapy to patients to treat a variety of symptoms or conditions such as chronic pain, tremor, Parkinson's disease, epilepsy, incontinence, or gastroparesis. Implantable neurostimulators may deliver neurostimulation therapy in the form of electrical pulses via implantable leads that include electrodes. To treat the above-identified symptoms or conditions, implantable leads may be implanted along nerves, within the epidural or intrathecal space of the spinal column, and around the brain, or other organs or tissue of a patient, depending on the particular condition that is sought to be treated with the device.
With respect to implantable leads, several elements such as conductors, electrodes and insulators may be combined to produce a lead body. A lead may include one or more conductors extending the length of the lead body from a distal end to a proximal end of the lead. The conductors electrically connect one or more electrodes at the distal end to one or more connectors at the proximal end of the lead. The electrodes are designed to form an electrical connection or stimulus point with tissue or organs. Lead connectors (sometimes referred to as terminals, contacts, or contact electrodes) are adapted to electrically and mechanically connect leads to implantable pulse generators or RF receivers (stimulation sources), or other medical devices. An insulating material may form the lead body and surround the conductors for electrical isolation between the conductors and for protection from the external contact and compatibility with a body.
Such leads may be implanted into a body at an insertion site and extend from the implant site to the stimulation site (area of placement of the electrodes). The implant site may be a subcutaneous pocket that receives and houses the pulse generator or receiver (providing a stimulation source). The implant site may be positioned a distance away from the stimulation site, such as near the buttocks or other place in the torso area. One common configuration is to have the implant site and insertion site located in the lower back area, with the leads extending through the epidural space in the spine to the stimulation site, such as middle back, upper back, neck or brain areas.
Current lead designs have different shapes, such as those commonly known as paddle leads and percutaneous leads. Paddle leads, which are typically larger than percutaneous leads, are directional and often utilized due to desired stimulus effect on the tissues or areas. However, current paddle leads require insertion using surgical means, and hence, removal through surgical means. Percutaneous leads are designed for easy introduction into the epidural space using a special needle. Therefore, such leads are typically smaller and more nearly circular in cross-section than paddle-shaped leads. This reduced size facilitates their implantation in the body, allows their implantation into more areas of the body, and minimizes the unwanted side effects of their implantation.